The Logitech T-BC21 Trackman Trackball USB Mouse is a versatile and reliable input device for computers. With a maximum DPI of 300 and ergonomic design, this trackball mouse offers precise and comfortable control. Featuring programmable buttons and a trackball for smooth tracking, this gray mouse from Logitech is a practical choice for those looking for a quality USB mouse with a unique trackball design. Whether you are a long-time fan of trackball mice or looking for a new option, the Logitech T-BC21 is a tested and functional choice for your computing needs.